Device for feeding and cutting film in machines for conditioning products

ABSTRACT

A device for feeding and cutting a continuous film ( 2 ) to a station ( 5 ) for wrapping products ( 4 ) is applied to a conditioning machine or line ( 3 ) comprising a station ( 6 ) for positioning and feeding products ( 4 ) which are mobile, one after another and in a direction of feed (V), on a conveyor surface ( 7 ) along the machine ( 3 ) between the positioning station ( 6 ) and the wrapping station ( 5 ). The film ( 2 ) is located between the surface ( 7 ) and the base ( 4   a ) of the products ( 4 ), where they pass close to a first slot ( 25 ) in the conveyor surface ( 7 ), and the film ( 2 ) proceeds as one with the products ( 4 ) along the surface ( 7 ). The conditioning line ( 3 ) also comprises cutting means ( 13 ) for forming a piece ( 2   a ) of film ( 2 ), these means being located at the conveyor surface ( 7 ), downstream of the first slot ( 25 ) and upstream of the wrapping station ( 5 ) according to the direction of feed (V). The cutting means ( 13 ) operate at the gap between successive products ( 4 ).

BACKGROUND OF THE INVENTION

The present invention relates to a unit for feeding and cutting film onmachines for conditioning products, in particular products which mainlyhave a cylindrical or prismatic shape which are wrapped with heat-shrinkmaterial.

At present automatic machines of the above-mentioned type have anoperating line basically equipped with stations for positioning productsand forming predetermined groups of said products, followed, furtherdownstream according to a direction of feed of the products, by stationsfor wrapping the groups in plasticized wrappers.

The intermediate positioning and forming stations are therefore designedto form predetermined groups of products and to transport them towardsthe wrapping stations.

Once wrapped, the group of products leaves the station and, by means ofa conveyor line, reaches a packaging station where said wrapping processis completed. The plasticized wrapper, preferably made of heat-shrinkfilm, is heated so that it tightly adheres to the group of products.

The product wrapping stations therefore have a system for supplying thefilm, which normally comes from a special feed and cutting stationlocated below the product conveyor surface.

Therefore, this station is connected to suitable conveyor devices forbringing the film to the product conveyor surface, where the wrapper isformed by wrapping the film around the products.

A construction solution for such a film feed and cutting station isdescribed in patent EP-491666.

Said solution involves a cutting unit with means for supporting andmoving a knife consisting of a pair of chains, parallel and opposite oneanother, supporting the knife rigidly and on both sides, closed in aring on a corresponding pair of gear wheels, one of which ismotor-driven.

The pair of chains structured in this way allows continuous movement ofthe knife, through an almost oval path, cyclically bringing the knifeinto a position in which it makes contact with and cuts a piece of film.

In said solution, the cutting unit is located below the operating linewhere the products pass, and the conveyor devices comprise amotor-driven angled surface which, as indicated, supplies the wrappingstation with film.

A second solution described in patent EP-581747, has a structurecomprising a knife located immediately below the product conveyorsurface and a set of film feed rollers located upstream of the kniferelative to the direction of film feed.

To cut the film, the knife which extends transversally to the machine,is moved along a straight line, in both directions, basically actinglike a guillotine on the film.

Said solutions were further modified to obtain effective “continuouscycle” operation in packaging and the machine is described in patentEP-839723.

In the latter solution, the device for feeding and cutting film has apair of counter-rotating rollers between which the film passes.

The first roller in the pair has a knife projecting radially from theroller, whilst the second roller has a radial groove housing the knifeduring a cutting rotation.

However, the above-mentioned machines have some disadvantages inparticular due to the positioning, relative to the rest of the machine,of the many components in the station and the consequent architecture ofthe devices which supply film to the wrapping station.

Since they must satisfy high parameters for synchronization with productfeed on the operating line, such devices have a rather complexstructure. Said structure must also guarantee a continuous supply offilm to the subsequent stations, usually pushing the film upwards,since, as already indicated, they are normally located below theconveyor surface.

The complexity of the devices therefore means that their cost is high,placing such machines in a niche in the market reserved for those withproportionate investment budgets.

SUMMARY OF THE INVENTION

The aim of the invention is, therefore, to overcome the afore-mentioneddisadvantages, with a device for feeding and cutting film in a machinefor conditioning products which has a simple and economical structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical features of the present invention, in accordance with theaforesaid aims, may be clearly inferred from the claims herein, inparticular claim 1 and, preferably, from any of the claims directly orindirectly dependent on claim 1.

The advantages of the present invention are more clearly illustrated inthe detailed description which follows, with reference to theaccompanying drawings, which illustrate a preferred embodiment withoutlimiting the scope of application, and in which:

FIG. 1 is a schematic side view with some parts cut away to betterillustrate others of a machine for conditioning products comprising adevice made according to the present invention;

FIG. 2 is a schematic front view with some parts in cross-section of adetail of the device made according to the present invention;

FIG. 3 is a schematic side view with some parts cut away to betterillustrate others of a different embodiment of the device made accordingto the present invention;

FIG. 4 is a schematic top plan view with some parts cut away for greaterclarity of a detail of the machine illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying drawings, and in particular withreference to FIG. 1, the numeral 1 denotes a device for feeding andcuffing a continuous film 2 to a machine or line 3 for conditioningproducts 4.

In particular, said machine 3, in a generic standard configuration,comprises a station 5 for wrapping the products 4 and a station 6 forpositioning and supplying the products 4 to the subsequent stations.Said stations 5 and 6 are basically of the known type and so are notdescribed in further detail in this text.

The device 1 comprises a conveyor surface 7, mobile in a direction V offeed, supporting the products 4 which normally have a base 4 a on whichthey rest.

In particular with reference to FIG. 1, it can be seen how the device 1comprises a single conveyor surface 7, formed by the upper branch 8 of abelt 9 wound in a loop about a plurality of rollers 10 of which at leastone is a driving roller and the others are driven rollers.

In greater detail, it may also be seen that the device 1 comprises a setof rollers 10 a arranged in such a way that, extending as it does, theupper branch 8 forms a transversal slot 11 in the surface 7,constituting a cutting line for the uses better described below. Saidrollers 10 a therefore form return means 10 a.

In embodiments not illustrated, the slot 11 may be formed by asuccession of two conveyor surfaces with the respective rear and frontends opposite and at a distance from one another.

As is also shown in FIG. 4, at the conveyor surface 7, and precisely theslot 11, there is a knife 13 which is transversally mobile along theslot 11. Basically, in the embodiment illustrated the knife 13 cutstransversally relative to the surface 7 or, in any case, transversallyto the direction V of feed of the products 4. In the particularembodiment illustrated, the knife 13 is “V”-shaped and has a doubleblade to allow the film to be cut in one direction and the other as itmoves along the above-mentioned cutting line. Advantageously, inembodiments that are not illustrated, the knife 13 may have any shapeand may even be substituted by a pair of knives, each with a singlecutting edge and designed to cut the film 2 in one direction only, asdescribed below.

In particular with reference to FIG. 2, it can be seen that the knife 13is supported by a bracket 14 rigidly connected to a support 15 engaging,by means of a counter-support 16, with a toothed belt 17 wound in a looparound a pair of pulleys 18, only one of which is visible in theaccompanying drawings.

The pulley 18 is connected to a motor M for moving the belt 17, togetherwith the knife 13, transversally to the surface 7, to form a piece 2 aof film 2.

A sliding element 19 supports the counter-support 16 and is slidablyconnected to a guide 20, which is also consequently positionedtransversally to the conveyor surface 7.

Opposite the knife 13 there is a pair of pneumatic pistons 21, visiblein FIGS. 1 and 3, to hold the film 2 during the cutting operations, bymeans of a forked pad 21 a which allows the knife 13 to pass.Advantageously, there may be any number of pistons 21 according to themachine 3 requirements and the size of the film 2 used to wrap theproducts 4. As described, said pistons 21 constitute presser means.

With reference to FIG. 1, it may be seen that in the case illustratedthe film 2 is wound in a reel 22, located, in the particularconfiguration illustrated and by way of example only, below the surface7.

A motor-driven roller 23 is positioned at a tangent to the reel 22 andforms, as described in more detail below, film 2 unwinding means 24.

During normal use, the film 2 unwound from the reel 22 according to anunwinding path S reaches the conveyor surface 7 through a slot 25 and isheld on the surface 7 by the weight of the products 4.

Said unwinding path S is formed by a plurality of guide rollers 26 forthe film 2. Three of these rollers 26 are illustrated, althoughadvantageously there may be any number of them, according to theparticular requirements of the machine 3.

The device 1 also comprises a sonar 27 and a unit 28 for the emission offluid, normally compressed air 29, located downstream of the reel 22according to the direction of unwinding S1, to prevent, as is clarifiedbelow, film 2 tensioning when the film 2 is unwound from the reel 22, bythe unwinding means 24 and the products 4 are fed on the conveyorsurface 7 downstream of the slot 25 since the products 4 pull the film2, as described below.

In particular, the sonar 27 is designed to detect said tensioning and,by blowing an air jet 29, the device 28 can form a loop 30 in the film2, so that it basically creates a film 2 reserve 31 along the unwindingpath S.

The sonar 27 and the device 28 basically constitute safety means 32. Inembodiments not illustrated, such safety means 32 may comprise otherdevices of a substantially known type, all designed to form a film 2reserve 31.

The device 1 has sensor means 33 positioned along the film 2 unwindingpath S to synchronize film 2 unwinding with product 4 feed. Said means33 comprise a first photocell 34 aligned with the film 2, locatedupstream of the slot 25 according to the direction of unwinding S1.

As described below, the photocell 34 synchronizes product 4 feed withthe film 2 if the latter has a printed motif to be positioned relativeto the products 4 when they are wrapped in a piece 2 a of film.

In particular, in these cases the film 2 has a reference elementidentifiable by the photocell 34, which may be the above-mentionedprinted motif, a mark on the film 2 or any reference on the film 2. Thephotocell 34 is slidably connected to a guide 35 and is mobile between afirst position, corresponding to a minimum size of the piece 2 a of film2 which will be used to wrap the products 4 and a second position,illustrated with a dashed line in FIG. 1, corresponding to a maximumsize of the piece 2 a of film.

A second photocell 36 is located, at the conveyor surface 7, downstreamof the slot 25 and upstream of the knife 13 according to the direction Vof product 4 feed. This second photocell 36 operates in conjunction witha separator element 37 of the positioning and supply station 6 to form agroup 38 of products 4, according to a substantially known method, notdescribed in detail. The photocell 36 is mobile on a guide 39 between aposition distanced from the knife 13 and a position substantially closeto the knife 13, illustrated with a dashed line in FIG. 1, so that itcan form groups 38 consisting of a predetermined desired number ofproducts (conditioning the groups of products).

The sensor means 33 also comprise a third photocell 40 located close tothe conveyor surface 7, downstream of the knife 13 and upstream of thewrapping station 5, according to the direction V of feed, to establishthe length of the piece 2 a of film which will be used to wrap the group38 of products 4 if the film 2 does not have any motif to be centeredwith the group 38 during wrapping. Hereinafter this type of film 2 iscalled “transparent”.

The photocell 40 is also mobile on a respective guide 41, extendingsubstantially parallel with the surface 7, between a minimum sizeposition, illustrated with a dashed line in FIG. 1, corresponding to aminimum measurement of the piece 2 a of film 2 that will be used to wrapthe products 4, and a maximum size position, corresponding to a maximummeasurement of the piece 2 a of film.

Finally, the device 1 comprises a fourth photocell 42 locatedimmediately upstream of the knife 13 and designed to confirm alignmentof the products 4 with the cutting line.

In particular with reference to FIG. 3, it may be seen that the knife13, together with the bracket 14, the support 15, the counter-support16, the belt 17, the pulleys 18, the sliding element 19 and relativeguide 20, the pneumatic pistons 21, the motor M and the return rollers10 a may be installed on a carriage 43, mobile at the same speed as thesurface 7, along a respective guide 44 in the direction V of productfeed, between a start of stroke position, where a cut in the film 2begins, and an end of stroke position, not illustrated, where the cutends.

As described below, this embodiment allows “continuous” use of themachine 3, that is to say without interruption in the supply of products4 to the wrapping station 5.

Obviously, if knife 13 movement along paths not completely perpendicularto the surface 7 is required, different speeds V1 and V2 may becalculated, respectively for the carriage 43 and the surface 7 again toallow a transversal cut, but with different speeds and, therefore,machine 3 productivity.

Similarly (see FIGS. 3 and 4), second presser means 100 may be used,acting on the film 2, downstream of the first slot 25 relative to thedirection V of feed, so that the film 2 can be held in place even whenthere are no products 4 on the surface 7, for example for sizechange-overs in the groups of products 4 to be formed. These secondpresser 100 may consist, for example, of pistons 101 with end pads 102which make contact with the film 2.

In practice, starting with a generic operating configuration, at thepositioning station 6 outfeed, the respective bases 4 a of the products4 make contact with the film as it reaches the conveyor surface 7 asthey pass over the slot 25.

The film 2 below is unwound from the reel 22 by the roller 23 and above,at the surface 7 level, is held and pulled by the products 4 resting onthe surface 7.

To avoid unwanted film 2 tensioning after product 4 feed on the surface7, each time it detects such tensioning, the sonar 27 activates thedevice 28, which, by blowing on the film 2 unwound from the reel 22,creates the reserve 31 in the form of the loop 30.

If the film 2 has a printed motif on it, which must be suitably centeredrelative to the products 4 when packaging is complete, the photocell 34synchronizes film 2 unwinding with product 4 feed on the surface 7.

Simultaneously, the photocell 36 dedicated to sizing the groups 38,activates the separator element 37 to form the group 38 with which theprinted film 2 size unwound from the reel 22 is associated. In normaloperating conditions, the group 38 stops in front of the cutting lineand the photocell 42 confirms that alignment has been achieved.

In particular with reference to FIG. 4, the products 4 are fed beyondthe cutting line, still pulling the continuous film 2, until they reacha position where a trailing section 2 b of film 2 which will form thepiece 2 a of film after the cut, substantially between the front 4 b ofthe products 4 and the cutting line, is long enough to wrap the group 38(advantageously the trailing section 2 b is longer than the perimeter ofthe group of products 4 in the side view in FIG. 1). Once the products 4are positioned, the pistons 21 block the film relative to the knife 13which cuts the film 2, moving transversally to the surface 7, formingthe piece 2 a of film. If the knife 13 is of the type with two blades,it will make the cut in direction T1 and, for the next group 38 ofproducts, a cut in the film 2 in direction T2, without having to returnto a starting position at the end of each cut.

The products 4 together with the piece 2 a of film are then fed towardsthe wrapping station 5, where a plasticized wrapper is formed around thegroup 38 of products using known methods that are therefore notdescribed.

If the film 2 is transparent, to form the piece 2 a of film thephotocell 40 will check the distance between the products 4 and thecutting line, and the film 2 is cut when the trailing section 2 b offilm 2 is long enough to wrap the group 38.

In the device illustrated in FIG. 3, the film 2 is cut during a carriage43 movement in the direction V of product feed. The carriage will moveat a speed equal to that of the surface 7 so that the cutting line isrelatively stationary relative to the products 4 and to the film 2 to becut. The movement of the carriage will also be such that it allowscarriage 43 repositioning in the start of stroke position when a newgroup 38 of products 4 arrives, pulling the film 2, close to the cuttingline.

The entire operation of the machine 3 is regulated by a control unit,not illustrated, which processes the signals arriving from thephotocells described. The many adjustments and size variations may besimply performed by changing the position of the photocells or, in amore complex way, by operating on the machine 3 software programming.

The invention fulfils the preset aims. Positioning the knife at theconveyor surface, downstream of the slot from which the film arrives andupstream of the wrapping station according to the direction of productfeed on the conveyor surface, the structure of the machine can besignificantly simplified, since the film, simply unwound from the reel,is basically pulled towards the cutting line by the products themselves.

Moreover, the positioning of the photocells described allows the use ofboth printed film and transparent film and product size change-overs aresimple to perform by manually positioning the photocells.

The invention described is suitable for evident industrial applications.It may be modified and adapted in several ways without thereby departingfrom the scope of the inventive concept. Moreover, all details of theinvention may be substituted by technically equivalent elements.

1) A device for feeding and cutting a continuous film (2) to a station(5) for wrapping products (4) in a conditioning machine or line (3)comprising a product (4) positioning and feed station (6), the products(4) being mobile, one after another and in a direction (V) of feed, onat least one conveyor surface (7) along the machine (3) between thepositioning station (6) and the wrapping station (5), the film (2) beinglocated between the surface (7) and the base (4 a) of the products (4),where the products pass close to a first slot (25) in the conveyorsurface (7) and proceeding as one with the products (4) along thesurface (7), the device comprising cutting means (13) for forming apiece (2 a) of film (2), the cutting means being located at the conveyorsurface (7), downstream of the first slot (25) and upstream of thewrapping station (5) according to the direction (V) of feed, the cuttingmeans (13) operating at the gap between successive products (4). 2) Thedevice according to claim 1, comprising return means (10 a) forming asecond slot (11) in the conveyor surface (7) for the passage of a knife(13), transversally mobile relative to the conveyor surface (7), andforming the cutting means (13). 3) The device according to claim 1,comprising return means (10 a) forming a second slot (11) in theconveyor surface (7) for the passage of a knife (13), transversallymobile relative to the direction (V) of feed and forming the cuttingmeans (13). 4) The device according to claim 2, comprising presser means(21) located at the cutting means (13), on opposite sides of the cuttingmeans (13), to block and hold the film (2) relative to the cutting means(13) for formation of the piece (2 a) of film. 5) The device accordingto claim 4, wherein at least the cutting means (13), the return means(10 a) and the presser means (21) are mobile along the direction (V) offeed, parallel with the conveyor surface (7) and simultaneously with theproducts (4) and the film (2), from a start of stroke position, where acut in the film (2) begins, to an end of stroke position, where the cutfinishes. 6) The device according to claim 4, wherein at least thecutting means (13), the return means (10 a) and the presser means (21)are mobile along the direction (V) of feed, parallel with the conveyorsurface (7) and with a speed (V1) different to the speed (V2) of theproducts (4) and of the film (2), from a start of stroke position, wherea cut in the film (2) begins, to an end of stroke position, where thecut finishes. 7) The device according to claim 5, comprising a carriage(43), supporting the cutting means (13), the return means (10 a) and thepresser means (21), and a first guide (44) extending along the machine(3), the carriage (43) being slidably connected to the guide (44). 8)The device according to claim 4, wherein the presser means (21) compriseat least one pneumatic piston (21) designed to control at least one pairof fork-shaped pads (21 a). 9) The device according to claim 1, whereinat the surface (7) there are second presser means (100) acting on thefilm (2), downstream of the slot (N) relative to the direction (V) offeed, and designed to allow the film (2) to be held in the absence ofthe products (4) on the surface (7). 10) The device according to claim1, including a reel (22) supporting the film (2) and means (24) forunwinding the film (2) from the reel (22), comprising safety means (32),located downstream of the reel (22) according to a direction (S1) offilm (2) unwinding, to prevent film (2) tensioning when the film isunwound simultaneously with feeding of the products (4) on the conveyorsurface (7), downstream of the first slot (25), the products pulling thefilm (2) along the surface (7). 11) The device according to claim 10,wherein the safety means (32) comprise at least a first unit (28)designed to form a reserve (31) of film (2) downstream of the reel (22)according to the direction (S1) of unwinding. 12) The device accordingto claim 11, wherein the first unit (28) operates by emitting fluid tocreate a loop (30) in the film (2), the loop (30) forming the reserve(31). 13) The device according to claim 10, wherein the safety means(32) comprise a sonar (27) opposite the film (2), for detecting film (2)tensioning. 14) The device according to claim 1, comprising sensor means(33) located along a film (2) unwinding path (S) designed to operate inconjunction with, respectively, the positioning and feed station (6), toform a group (38) of products (4), and with the cutting means (13) andthe conveyor surface (7), to form the piece (2 a) of film. 15) Thedevice according to claim 14, in which the film (2) has a referenceelement in predetermined sequences, wherein the sensor means (33)comprise at least a first photocell (34) for identifying the referenceelement, aligned with the film (2), located upstream of the first slot(25), according to a direction (S1) of film (2) unwinding (2), forchecking synchronization between the film (2) and the size of theproducts (4) in transit, close to the first slot (25) so as to allowcentering of the film (2) and the group (38) of products (4). 16) Thedevice according to claim 15, wherein the first photocell (34) is mobilealong a second guide (35), extending parallel with the film (2), betweena first position, corresponding to a minimum size of the piece (2 a) offilm and a second position, corresponding to a maximum size of the piece(2 a) of film. 17) The device according to claim 14, wherein the sensormeans (33) comprise a second photocell (36) located at the conveyorsurface (7), downstream of the first slot (25) and upstream of thecutting means (13) according to a direction (V) of feed, forming thesize of the group (38) of products (4) on the conveyor surface (7),operating in conjunction with a separator element (37) of thepositioning and feed station (6). 18) The device according to claim 17,wherein the second photocell (36) is mobile on a third guide (39)between a position distanced from the cutting means (13) and a positionclose to the cutting means (13) forming respective sizes. 19) The deviceaccording to claim 14, in which the film (2) is of the transparent type,wherein the sensor means (33) comprise a third photocell (40) locatedclose to the conveyor surface (7), downstream of the cutting means (13)and upstream of the wrapping station (5) according to the direction (V)of feed, to establish a length, that is to say the size, of the piece (2a) of film for wrapping the group (38). 20) The device according toclaim 19, wherein the third photocell (40) is mobile on a fourth guide(41), extending parallel with the film (2), between a minimum sizeposition, corresponding to a minimum size of the piece (2 a) of film anda maximum size position, corresponding to a maximum size of the piece (2a) of film. 21) The device according to claim 1, comprising a fourthphotocell (42) located immediately upstream of the cutting means (13)according to the direction (V) of feed, for checking alignment of theproducts (4) and the film (2) with the cutting means (13).